In 2011 they invited Sam to their Westminster Abbey wedding and Sam – whose relatives include Shell Oil founder, the 3rd Viscount Bearsted – made Kate guest of honour at his nuptials to party-organiser Bella Ballin.

Healthcare businessman Sam won the Cheltenham Gold Cup in 2010 on Long Run and they are hotly-fancied for the 4 mile, 30-fence race.

Meanwhile Zara and mother Princess Anne are cheering on Monbeg Dude – after it was bought by Tindall when merry at an auction.

The then England rugby ace, now 35, was so "well-oiled" he was not even facing the sales ring when he and two rugby mates bought the £12,000 nag at a Cheltenham auction.

Zara reportedly branded Tindall an "idiot" after watching in horror on the horse's first outing – as it failed to jump.

But while pregnant with their first child Mia, Zara spent time riding Monbeg Dude and now believes he may be too strong for rivals at the 4.15pm event.